Patience is key to building a great deep sky image

It’s not been a great summer so far, weather wise, which is really frustrating as I am a teacher and I get 6 weeks off every summer. What I want to be doing is imaging however, in Yorkshire, the weather has been terrible: rain, cloud, more rain … which teaches a valuable lesson – patience is most definitely a virtue; especially in astrophotography.

About a month ago, I made a start on NGC 7380, The Wizard Nebula. I was pretty impressed at how much detail I was getting on narrowband, especially given that it was mid summer and full moon. This is a stack of only 18 minutes of Hydrogen Alpha, imaged on my QHY163m camera, using unity gain of 139, offset 21 @ 180 second exposure.

The Wizard Nebula in Ha - 18 mins total exposure
The Wizard Nebula in Ha – 18 mins total exposure

I finally managed to get some clear skies last night although I managed to waste about 2 hours messing about with kit I really should have had tested as working before it got dark. I began imaging about 2am and let it run until 3.30am when it began to get noticeably lighter. I was gathering O3 data this time and managed to keep 18×3 minute subs out of all the data gathered.

I calibrated this in Pixinsight then croppped and aligned it to the Ha data already gathered and calibrated previously. The first problem was the rotation of the previous image compared to the latest data – I had to crop quite severely to allow for alignment.

I created a bi-colour image with a synthetic green channel made by combining the Ha and O3 data in Pixinsight. The image was then colour calibrated, with the background neutralised. I applied a masked noise reduction process on the background before reversing the mask and bringing out the finer details of the nebula. Finally, I applied a curves transformation on the background to increase the contrast and darken the background slightly.

The result is a bi-colour image that is a total of 1.2 hours integration of narrowband information gathered from a heavily light polluted area of north England. I plan to continue to add to the folder and hopefully complete another couple of hours on each channel, including S2, before the end of August. As a working piece, I am very happy with it so far:

Ha and O3 bicolour process of NGC 7380
Ha and O3 bicolour process of NGC 7380

I’m really impressed with my mount, the Skywatcher EQ6-R pro – it is helping me guide much more accurately and I am now getting to grips with EQMod as an alternative to using the handset. I’m still fine tuning PHD2 to work with it and my guide scope / camera configuration from AltairAstro so hopefully I can continue to refine my guiding and imaging processes.


2 thoughts on “Patience is key to building a great deep sky image

Leave a Reply